Rieger syndrome (RS) is an autosomal dominant disorder of morphogenesis characterized by abnormalities of the anterior segment of the eye and dental hypoplasia. Other systemic anomalies have been reported in association with the syndrome, the most common of which are mild craniofacial dysmorphism, including maxillary hypoplasia and failure of involution of the periumbilical skin and omphalocele. Gastrointestinal defects reported include Meckels diverticulum (Krespi, Y. P. and D. Pertsemlidis (1979) Am. J. Gastroenter. 71:608–610) colon atresia (Rogers, R. C. (1988) Proc. Greenwood. Genet. Center 7:9–13) and anal stenosis (Crawford, R. D. (1967) Brit. J. Ophthalmol. 51:438–440) The ocular features can include a prominent, anteriorly displaced Schwalbe line, iris processes which insert into the Schwalbe line, hypoplasia of the anterior iris stroma or corectopiea and pseudopolycoria. Roughly one-half of the patients will develop glaucoma, usually by young adulthood. The dental features associated with the condition include oligodontia and microdontia.
There is general agreement that patients with both the ocular features and systemic abnormalities (dental, umbilical, craniofacial) should be designated Rieger syndrome. The nomenclature of patients with only the ocular features, however, is confusing and disputed. For example, the condition of only ocular abnormalities is sometimes referred to as Rieger syndrome and other times referred to as Axenfeld-Rieger anomaly.
The underlying genetic defect and the chromosomal localization of RS is uncertain. Cases with Axenfeld-Rieger anomaly have been reported with various aberrations of chromosomes 4, 6, 10, 13, 16, and 22 (Wilcox, L. M. et al., (1978) Am. J. Ophthalmol. 86:834–839; Tabbara, K. F. et al. (1973) Canad. J. Ophthal. 8:488–491; Herve, J. et al. 1984) Ann. Pediatr. 31:77–80; Stathacopoulas, R. A. et al. (1987) J. Ped. Ophthalmol. Strabismus 24:198–203; Akazawa, K. et al. (1981) J. Ophthalmol. 105:323; Furguson, J. G. and E. L. Hicks (1987) Arch. Ophthal. 105:323; Heinemann, M. et al. (1979) Br. J. Ophthalmol. 63:40–44). Four cases of fully developed RS, including the dental and umbilical anomalies, have been associated with deletions in the region of chromosome 4q23–26. One case of a deletion in the region of 4q26 which did not have RS has also been reported. These cases indicate that a gene for RS lies in the region of 4q25.
In RS, a high risk of developing increased intraocular pressures and subsequent glaucomatous damage necessitates vigorous screening procedures beginning in infancy. Current screening for the ocular abnormalities of RS requires slit lamp examination, tonometry, gonioscopy and a dilated examination of the optic nerve head.